Do small-sided games prepare players for the worst-case scenarios of match play in elite young soccer players?

The aim of the study was to determine whether the physical performance of young soccer player during various small sided games (SSGs) underloads, replicates or overloads the requirements of the worst-case scenarios (WCS) during match play. A total of 521 SSGs’ individual observations and 15 different formats of SSGs with different areas per player (ApP) (ApP100: < 100; ApP200: ranged from 101 to 200; ApP300: > 201, all in m2 · player-1) were taken into consideration. Whole (90-min average; OM) and 15-, 5- and 1-min worst-case scenarios (WCS15, WCS5 and WCS1, respectively) were analysed. Total distance covered relative (m · min-1) (TDCR), high-speed distance relative (m · min-1) (HSDR), very high-speed distance relative (m · min-1) (VHSDR) and sprint distance relative (m · min-1) (SDR), player load relative (PLR) and both total (ACCR) and high intensity relative accelerations (n · min-1) (ACCHR) were collected. All external load measures analysed were significantly higher in WCS1 compared to WCS of longer duration and SSGs with different ApP (p < 0.001). The analysis demonstrated interactions between game type and player positions (p < 0.001) for TDCR, VHSDR, PLR and ACCHR. The SSG formats did not sufficiently stimulate the WCS for locomotor demands (VHSDR and SDR). SSGs played on an ApP100 overestimated the mechanical values compared to WCS15 and WCS5. The analysed SSG formats did not sufficiently stimulate players to cope with all external load demands that occurred during WCS1. This study provides useful information for practitioners on the heightened impact of different SSG formats on external load in relation to the WCS of competitive match play.


INTRODUCTION
Small sided games (SSGs) are currently one of the most common tasks used to enhance players' soccer-specific technical, tactical, and physical skills [1].In fact, SSGs allow players to replicate specific physical, technical, and tactical defensive and offensive behaviours without having to repeat mechanical movements [2].According to previous scientific literature, the physical performance and the development of fatigue in SSGs vary depending upon several variables [1,2].Two of the most often used constraints in designing SSGs are the number of players and the pitch size [3].When both variables are combined, the area per player (ApP) is obtained.It is a key concept during this type of task and it is defined as the theoretical pitch area that corresponds to each player; it is determined as the total pitch area divided by the number of players on the pitch [4].From a practical perspective, previous research revealed that large areas lead to an increase in total distance, total distance per minute, distance at different intensities, and sprint frequency [4,5].However, controversy exists regarding accelerations and Do small-sided games prepare players for the worst-case scenarios of match play in elite young soccer players?
Norwegian professional players indicated that HSD during 4vs4 and 6vs6 was 78% and 86% lower than in the peak period of match play, showing that this type of SSGs could underestimate high-intensity activities reported during the WCS.It seems that the distance, HSD and distance covered when sprinting are the variables that have the lowest percentage of most demanding passages while performing the game formats studied, especially in the smallest formats of training games [16].Meanwhile, with elite young players, Sydney et al. [17] mentioned that no SSGs of different sizes were found to replicate the peak of total distance and HSD during match-play.However, these authors only considered two locomotor variables (total distance and HSD).In agreement with Martin-Garcia et al. [16] we believe that using more time windows (e.g., 1, 5, and 15 minutes) would have made it possible to explore in greater depth how the values relating to the competition percentage vary.In consequence, more research in young players using more WCS time windows and considering more variables is needed.
Hence, the objective of this study was to determine whether the physical performance of young soccer players during various SSGs underloads, replicates or overloads the requirements of the worstcase scenarios during match play.The conclusions of the present study would make it possible to manage the ApP used during SSG to underload, replicate or overload the requirements of the worstcase scenarios during match play and plan the whole-session training load during practice.

Subjects
The data for this study were collected from players belonging to an elite Spanish soccer academy (n= 31; age = 17.0 ± 1.3 years; height = 173.7 ± 6.0 cm; body mass = 66.9 ± 7.1 kg and body fat percentage = 10.6 ± 1.0%).Goalkeepers were excluded from the data collection.The club's medical staff certified the health status of each player.Injured players diagnosed by medical services or recently, Pinheiro et al. [12] stated that with professional soccer players the total distance per minute was higher during friendly matches than during different formats of SSGs.Additionally, no differences were found between friendly matches and SSGs considering mechanical values (number and average distance of accelerations).
Another group of authors compared different SSGs with OMs [13] and found that only large-sided games (9vs9; 194 m 2 • player¯1) simulated the official full match more accurately than other sided games in terms of sprinting.Medium and SSGs were more intense than full matches considering mechanical values.However, these studies took into account physical performance variables for whole matches.Whilst reporting half or whole-match activities is useful to help understand overall physical loading, such data do not reflect the stochastic nature of soccer match-play [14].Therefore, considering the most intense periods of the competition could be valuable when managing the TL.
The worst-case scenarios (WCS) are defined as the periods of maximum physical output throughout the match [14].If the objective of training is to replicate or overload the movement demands reported during the competition, the use of WCS could be key to optimizing performance and adequately preparing the player for the matches.Hence, elucidating the demands associated with the WCS and comparing them with one of the most used tasks in training sessions (i.e., SSGs) may be useful when developing and scheduling specific training sessions.Although there are studies analysing the differences between SSGs and official competitions [6,13], to the authors' knowledge there is a gap in the literature examining the differences between SSGs and WCS during soccer competitions.Previous research [15,16,17] analysed the differences between SSGs and WCS.Nevertheless, only one previous study reported these differences considering young soccer players [17].This information may be useful for developing soccer-specific training programmes designed to condition youth players to cope with potentially decisive periods of matches.The first group of authors with senior   (> 25 km • h¯1) distance m) relative (SDR).The total number (per minute) of accelerations (ACCR) and the total number of high-intensity accelerations (ACCHR) (> 3 m • s¯2) were also gathered [5,20].
Moreover, a global load indicator was included as a variable: player load per minute (PLR), which is a measure based on the tri-axial accelerometer measures and may serve as a complementary tool for measuring the load from activities misrepresented by time-motion analysis [15].
and long passing, and possession play (4 vs 4 plus 2 floaters).Matches were played on official fields (104 × 62 m, length × width, respectively).Both mean values and peak 15-, 5-, and 1-minute values were calculated.Hence, for each player and for each variable, the most intense phases of 15-, 5-, and 1-minute duration were calculated using rolling average methods [20].

External load variables
The running variables were obtained from the Global Positioning System (GPS).All external load measures were normalized as relative distance covered in one minute (m • min¯1) or the number of accelerations in one minute (n • min¯1) [21].Consistent with a previous ApP100 > ApP200, ApP300 Note: TDCR (total distance covered relative); HSDR (high speed distance relative); VHSDR (very high speed distance relative); SDR (sprint distance relative); PLR (player load relative); ACCR (the number of total accelerations relative); ACCHR (the number of high accelerations relative); WCS15 (worst case scenario of 15 minute of duration); WCS5 (worst case scenario of 5 minute of duration); WCS1 (worst case scenario of 1 minute of duration); ApP100 (Area per player < 100 m  3).
The differences between playing positions and game type taking into consideration TDCR, HSDR, VHSDR, and SDR are outlined in

Procedures
The participants undertook their traditional weekly training routine.
All training sessions were performed on artificial pitches and all training sessions were scheduled at the same time (16:30-18:45).
During both training sessions and OM, players' movements were recorded using a portable 10 Hz GPS device that also incorporates a 400 Hz tri-axial accelerometer (Playertek, Dundalk, Ireland).Acceleration activity was measured as a change in speed for a minimum period of 0.5 seconds with acceleration at least of 2 m • s¯2.These GPS devices seem to be valid and reliable for use in team sports [23] and they were used previously in soccer research [24].The GPS device was attached to the upper back of each player by means of a special harness, and according to the manufacturer's instructions, all GPS units were activated 10 minutes before the training sessions or OM began.

Statistical analysis
Descriptive statistics (mean ± SD and confidence intervals) are reported for all variables.The data were tested for normality using quantile-quantile plots (Q-Q plots) and the Kolmogorov-Smirnov test of normality.Linear mixed models were performed to analyse the differences between SSG formats (ApP100, ApP200 and ApP300),

RESULTS
Descriptive statistics for selected physical performance variables and differences between formats (different WCS, OM, ApP100, ApP200, and ApP300) are shown in Table 3 1.Significant differences between different WCS and various sided games considering total distance covered relative (TDCR); a: significant differences compared to ApP100; b: significant differences compared to ApP200; c: significant differences compared to ApP300; d: significant differences compared to OM; e significant differences compared to WCS15; f: significant differences compared to WCS5.

FIG. 2.
Significant differences between different WCS and various sided games considering high-speed distance relative (HSDR); a: significant differences compared to ApP100; b: significant differences compared to ApP200; c: significant differences compared to ApP300; d: significant differences compared to OM; e significant differences compared to WCS15; f: significant differences compared to WCS5.

FIG. 3.
Significant differences between different WCS and various sided games considering very high-speed distance relative (VHSDR); a: significant differences compared to ApP100; b: significant differences compared to ApP200; c: significant differences compared to ApP300; d: significant differences compared to OM; e significant differences compared to WCS15; f: significant differences compared to WCS5.

FIG. 4.
Significant differences between different WCS and various sided games considering sprint distance relative (SDR); a: significant differences compared to ApP100; b: significant differences compared to ApP200; c: significant differences compared to ApP300; d: significant differences compared to OM; e significant differences compared to WCS15; f: significant differences compared to WCS5.

FIG. 5.
Significant differences between different WCS and various sided games considering number of total high-intensity accelerations relative (ACCHR); a: significant differences compared to ApP100; b: significant differences compared to ApP200; c: significant differences compared to ApP300; d: significant differences compared to OM; e significant differences compared to WCS15; f: significant differences compared to WCS5.

FIG. 6.
Significant differences between different WCS and various sided games considering player load relative (PLR); a: significant differences compared to ApP100; b: significant differences compared to ApP200; c: significant differences compared to ApP300; d: significant differences compared to OM; e significant differences compared to WCS15; f: significant differences compared to WCS5.

DISCUSSION
The main purpose of this study was to determine whether the physical performance of young soccer players during various SSGs underload, replicate, or overload the requirements of the worst-case scenarios (WCS) during match play considering external load measures.
To the authors' knowledge, no previous study has analysed the differences between WCS and SSG according to ApP with young soccer players.Our main findings were that WCS5 and WCS1 showed significantly higher values than SSG formats (ApP100, ApP200, and ApP300) and OM taking into account locomotor variables (TDCR, HSDR, VHSDR, and SDR).However, no significant differences were found between WCS15 and SSGs when sprint distances were analysed in most playing positions.Regarding mechanical (ACCHR) Figure 7 shows the different SSG formats and OM, considering the relative load normalized across all three analyzed WCS for all players' positions together.The ApP100 format represents, 50, 70, and 80% compared to WCS1, WCS5, and WCS15 respectively for TDCR.
Taking into account VHSDR and SDR, ApP100 greatly underestimates the worst-case scenarios of match play (WCS1: 2 and 0%, WCS5: 7 and 2%, and WCS15: 11 and 3%, respectively).Considering mechanical values, the ApP100 format overestimated or reached similar values according to the worst-case scenarios for both ACCR (WCS1: 80%, WCS5: 120%, and WCS15: 140%) and ACCHR (WCS1: 50%, WCS5: 120%, and WCS15: 170%).The results obtained for the ApP200 format analysing TDCR were similar to what was observed in the ApP100 format.The ApP200 format represents 60, 80, and 80% compared to WCS1, WCS5, and WCS15 respectively for the above-mentioned variable.Considering high-intensity locomotor activities (HSDR and SDR), ApP200 did not exceed 30% compared to worst-case scenarios of match play (WCS1: 6 and 2%, WCS5: 20 and 7%, and WCS15: 30 and 10%, respectively).Regarding mechanical due to several factors such as the size of the pitch during SSGs.The frequent use of smaller pitch size (ApP100 and ApP200) during the training sessions could be behind these differences.In addition, the reduced peak VHSDR and SDR recorded in ApP300 compared to WCS could potentially be due to the time constraints, pacing strategies, and psychological or motivational factors resulting in fewer opportunities to reach similar values to those found in the most demanding phases of match play [17,34].According to Riboli et al. [6], we would need more than 350 m 2 • player¯1 to replicate the official match peaks of high intensity and sprint distance in elite adult players.In consequence, we could mention that SSGs do not prepare players adequately for the most demanding phases of competition, specifically for WCS1 and WCS5, in relation to VHSDR and SDR.
However, sided games with larger areas could be used to prepare WCS15 since no differences were found between WCS15 and SSG formats for each position analysed.Consequently, coaches and practitioners should consider the appropriate exposure of players to HSDR and SDR with the aim of either developing or maintaining their capacity to perform high-intensity efforts required frequently during WCS of match play [35].Thus, the results of this study show that supplementary high-speed running drills should be planned and periodized suitably concurrently with SSGs to prepare for WCS for young soccer players [36,37], specifically for positions with high demands of high-intensity and sprint distances (i.e.FB and WM).Additionally, this type of training could reduce the risk of non-contact hamstring injuries [38,39,40] and therefore should be considered in the practice.
Previous research concluded that accelerations and decelerations remained unchanged across different ApP used [6,41].Hence, no differences in accelerations and decelerations were found by Gaudino et al. [41] between SSGs with different areas per player.Conversely, we found that SSGs played on small areas (i.e., ApP100) had higher ACCHR values compared to WCS15 and WCS5 for all field positions, except for wide midfielders, where no differences were found.Wide midfielders reach the highest number of high-intensity accelerations during match play [16,42].Accordingly, similar values were observed between ApP100 and worst-case scenarios for this play position.However, it seems that SSG formats did not stimulate players sufficiently to cope with acceleration demands that occurred during WCS1 taking into consideration all play positions.We observed that players performed a higher number of both total and high-intensity accelerations per minute during ApP100 compared to WCS15 and WCS5.However, the greatest values were found during WCS1.Present data are in line with Dalen et al. [20], who observed that during SSG (4 vs 4) with professional soccer players, a higher number of ACCR was performed compared to the peak 5-minute intensity.Similarly, Martín-García et al. [16]  There were differences between worst-case scenarios and ApP formats for the players depending on their field position.WCS1 and WCS5 were higher for TDCR values compared to other formats across all playing positions.However, considering WCS15, we found that TDCR was higher than the ApP200 and ApP300 for all positions, except for midfielders.Maybe the greater distance per minute reached in this position during both training sessions [26] and during SSG formats compared to other positions [27,28] could explain these outcomes, since they are related to the positional role of linking defence and attack.These findings are in line with previous research [17,20].Therefore, these tasks seem less appropriate to replicate the most demanding phases of match play in the TDCR.Hence, SSGs with different ApP (ApP100, ApP200, and ApP300) reached 53, 57, and 60% respectively of TDCR of the WCS1.However, when using a bigger format (i.e., ApP300), the results showed similar values to different worst-case scenarios.Therefore, these tasks could be optimal to prepare TDCR worst-case scenarios of greater duration (i.e., WCS5 and WCS15).
In relation to high-intensity activities (i.e.HSDR, VHSDR), similar tendencies were found.HSDR and VHSDR were significantly higher in WCS1 and WCS5 compared to the different SSGs for all positions.However, no significant differences were found in HSDR and VHSDR between WCS15 and ApP200, and ApP300 for midfielders.A possible explanation for this fact could be that midfielders produce less HSDR and VHSDR during official matches [29]; hence, a lesser peak of 15 minutes was reached.In consequence, there are no differences between WCS15 and SSGs with larger area per player.Significant differences were found when we analysed the rest of the playing positions.FB and WM reached the greatest values during competitions in these variables; therefore, big differences exist between the most demanding passages and sided games.Regarding SDR values, WCS1 was higher than SSGs for all playing positions.Similarly, WCS5 was higher than SSGs for CD, FB, and WM, except for MF and FW.Once again, the shorter sprint distance reached for both positions during match play could be behind these outcomes.
Additionally, no differences were found between WCS15 and SSGs for most positions.Hence, SSGs could be a good solution when the practitioners aim to prepare the most demanding passages of 15 minutes duration.
Current soccer presents more high-intensity actions and greater sprint distances [30], being decisive in both attacking and defensive soccer situations, and they are considered a key measure of physical performance in soccer [31,32].In contrast, one of the most used tasks during the training process is the SSGs [33].However, the SDR and VHSDR observed during these types of drills were significantly lower than the demands observed in the worst-case scenarios of the competition taking into account different time periods in all playing positions.According to Dalen et al. [20], the discrepancy between SSGs and match peaks with respect to VHSDR and SDR could be Hence, an aggregate analysis between internal and external load would provide more accurate information.However, the impossibility of collecting the rate of perceived exertion after each SSG format during the daily real-life training routine may limit the opportunity to monitor consistently the internal and perceived load.

CONCLUSIONS
This study provides useful information for practitioners on the impact of SSG formats on physical load in relation to the WCS of competitive match play.The results highlight the importance of expressing the demands of the game formats relative to the WCS since we found that WCS5 and WCS1 were significantly higher than SSG formats (ApP100, ApP200, and ApP300) and OM taking into account locomotor variables (TDCR, HSDR, VHSDR, and SDR) and mechanical variables (ACCR, ACCHR, and PLR).In addition, larger SSG formats had greater TDCR and VHSDR values than smaller formats.However, when we analysed mechanical variables (ACCHR and PLR), we found that smaller SSGs
had higher values compared to larger SSGs and OM.Only the ACCHR values exceed the values in the WCS5 and WCS15 during ApP100 formats, while the demands of other measures do not do so in any cases.It seems that if the objective is reaching ACCHR values like WCS, ApP100 formats could be valid.However, it may be necessary to design other types of tasks when practitioners aim to reach locomotor values (TDCR, HSDR, VHSDR, and SDR) similar to the most demanding passages of match play.The present findings have several practical applications.In the first instance, to replicate the locomotor (TDCR, HSDR, and SDR) and mechanical values (ACCR, ACCHR, and PLR) reached during the WCS1 it seems that supplementary drills should be planned since the SSGs analysed did not cope with the physical demands of the most demanding phases of match play.Similarly, SSG formats with specific sprinting rules, individualized positional drills, transition-sided games, or running-based exercises seem to be needed when the objective is to reproduce VHSDR, and SDR values reached during WCS5.However, to prepare WCS15, sided games with larger areas could be a good choice since no significant differences were found between WCS15 and SSG formats for all positions analysed.The variables that have the lower percentage in relation to the most demanding phases of competition in all SSG formats studied, especially in the smallest formats of training games, are TDCR, VHSDR, and SDR.Lately, the different WCS during matches used in this study could be used as benchmarks to develop position-specific supplementary high-speed running training for elite young soccer players.This study provides useful information for coaches and practitioners on the impact of SSG formats on physical external load in relation to the WCS of competitive match play.The results highlight the importance of taking into account the most demanding passage of play to plan and periodize training load across the microcycle.Additionally, it seems important to compare match peaks with SSGs to assess the physical load imposed and include supplementary running drills if required.

TABLE 1 .
Number of observations of each SSGs, OM and WCS according to player positions.
Note: WCS15 (worst case scenario of 15 minute of duration); WCS5 (worst case scenario of 5 minute of duration); WCS1 (worst case scenario of 1 minute of duration); ApP100 (Area per player < 100 m 2

TABLE 2 .
Pitch size during small sided games.

Biology of Sport, Vol. 41 No1, 2024 105 Worst-case scenarios and sided games in young soccer players taking
into account our results, it seems that when aiming to prepare players for the most demanding phases of 1-minute duration a supplementary task emphasizing ACCR and ACCHR values may be needed, since the ApP formats analysed represented a maximum of 78 and 56% respectively, compared to WCS1.However, if the aim is to prepare WCS with a longer time window, it seems that both ApP100 and ApP200 SSG formats may be suitable.